Redemption requests include about one-third of clients’ money in the firm’s flagship fund

Clients have asked to pull about $1.5 billion from Visium Asset Management LP, a hedge-fund firm under investigation by federal authorities over alleged insider trading, people familiar with the matter said.

The redemptions, which include one-third of clients’ money in the firm’s flagship fund, are due to be paid by the end of the second quarter, these people said.